It may be too far this time, but East Texas has some really nice parks with plenty of pine trees:
Tyler State Park
Daingerfield State Park
Bob Sandlin State Park
Atlanta State Park
Brushy Creek, COE, Lake 'o the Pines
Buckhorn, COE, Lake 'o the Pines
2 nice COE campgrounds, Wright Patman Lake
And these are just those in the very Northeast corner of Texas -- about 150 miles east of Dallas. Most not far off I-20.
For what it's worth, east/west around Dallas is easy on I-20. I usually tow at highway speed with no slowdown. I must admit I've never encountered an accident; that would surely cause a slow-down.